Electron Spin Manipulation in Semiconductor Nanostructures – Alexander Efros

Date: Mon. January 26th, 2004, 12:30 pm-1:30 pm
Location: Rockefeller 221

Manipulating electron spin is one of the central problems in the growing field of semiconductor spintronics. This is of critical importance for quantum computing and information processing. Here I discuss the “optical initialization” and “optical read out” of the spin of an electron localized in a quantum dot [1]. We suggest using the combined effects of -optical pulses and transverse magnetic field for the optical pumping of the electron spin in QDs and the initialization of single spin Q-bit. The calculation shows that ~100% spin polarization can be reached as a result of several repetitions of this procedure. For “read out” of the single electron spin we suggest using a resonance fluorescence of trions excited resonantly by circularly polarized light, which was shown to suppress the electron spin relaxation. Generation of short intensive magnetic pulses is a difficult technical problem and recently the successful dynamic electric field manipulation of electron spin was demonstrated by Kato et al [2]. The authors used modulation of the electron g-tensor in the parabolic quantum well by an electric field. I will discuss a different mechanism of gate-voltage induced spin resonance based on the electron’s orbital motion and the standard mechanism of spin-orbit coupling [3].

[1] A. Shabaev, Al. L. Efros, D. Gammon, and I. A. Merkulov. Phys. Rev. B Rapid Communication, 68, 201305 (2003)

[2] Y. Kato, R. C. Myers, D. C. Driscoll, A. C. Gossard, J. Levy, and D. D. Awschalom, Science 299 1201 (2003)

[3] E. I. Rashba and Al. L. Efros, Phys. Rev. Lett. 91, 126405 (2003)